The present invention relates in general to paper sensors, and more particularly, to paper sensors associated with the hold down clips of tractor drive assemblies for fan fold paper.
It is common practice to print information from a computer on an elongated run of paper, typically referred to as a continuous or fan fold paper. Fan fold paper, as is well known in the art, is a continuous strip of paper having regularly spaced perforations along its longitudinal marginal edges to facilitate transport of the paper strip, and transverse alternating folds at predetermined intervals to establish substantially equal sized individual panels which can be folded upon one another. Recent electrostatographic reproduction apparatus have been designed with the capability of copying information contained on either individual documents or fan fold paper. An example of such apparatus is shown in U.S. Pat. No. 5,074,543 (issued Dec. 24, 1991, in the name of Lawniczak et al). In such apparatus, a motor driven tractor assembly is utilized to transport the fan fold paper such that it is fed across the platen of the reproduction apparatus. At appropriate times, the reproduction apparatus is activated in a well known manner to copy information from the individual panels of the fan fold paper.
It is, of course, clear that there must be some cooperative interrelation of the controls between the tractor drive assembly for the transport of fan fold paper and the reproduction apparatus in order to cycle the combined structure to obtain copies of the individual panels of the fan fold paper. In the past, location of sensors for determining the presence of fan fold paper has required that the paper be threaded through the sensors. This presents a potential for damaging the paper. Further, the presence sensors have been remotely located relative to the tractor drive assemblies. This may lead to an improper indication that the fan fold paper has actually been properly received in the tractor assemblies.